SEATTLE — SpaceX postponed the Jan. 6 launch of a Falcon 9 rocket because of a technical problem with the vehicle’s upper stage, delaying the delivery of supplies to the international space station and a demonstration of the potential reusability of the rocket’s lower stage.
Controllers halted the countdown less than 90 seconds before the scheduled 6:20 a.m. EST launch from Cape Canaveral Air Force Station, Florida, after identifying a problem with the thrust vector control system on the vehicle’s second stage. Because the mission has an “instantaneous” launch window, the hold scrubbed the launch attempt for the day.
In a statement issued shortly after the postponement, SpaceX, formally know as Space Exploration Technologies Corp., said “engineers observed drift on one of the two thrust vector actuators on the second stage that would likely have caused an automatic abort.” Launch controllers elected to postpone the launch to investigate the issue.
The launch is now tentatively rescheduled for Jan. 9 at 5:09 a.m. EST. Forecasts call for an 80 percent chance of acceptable weather at that time.
The Falcon 9 will launch a Dragon cargo capsule on the fifth of 12 planned missions to the ISS under the company’s Commercial Resupply Services contract with NASA. The spacecraft is carrying nearly 2,400 kilograms of supplies, hardware and experiments for the station.
The mission had been scheduled for December, but other technical problems, including an issue with a static-fire test of the rocket’s nine first-stage engines, forced SpaceX to postpone twice. Those delays, coupled with other factors including a high sun angle at the ISS that restricts operations there, pushed the launch to January.
The mission is particularly important to NASA because the other company with an ISS cargo delivery contract, Orbital Sciences Corp. of Dulles, Virginia, is recovering from the Oct. 28 loss of a Cygnus logistics spacecraft when its Antares launch vehicle failed shortly after liftoff. Orbital plans to launch a Cygnus mission in late 2015 on a United Launch Alliance Atlas 5 rocket before resuming launches of an upgraded version of Antares in 2016.
NASA’s ISS program manager, Michael Suffredini, said at a prelaunch press conference at the Kennedy Space Center Jan. 5 that NASA worked with SpaceX to maximize the amount of cargo on this Dragon mission. “The SpaceX folks used quite a bit a ingenuity to put items in all the little cracks and crevices as we kind of lean on the Dragon vehicle to supply ISS here for the next little while until the Orbital folks are flying again,” he said.
Suffredini also said that NASA has reduced the margin of consumables like food and water on the station from six to four months while Cygnus is unavailable. That reduction, he said, will free up space on Dragon missions to carry more research hardware.
The launch is significant not just for its payload, but also because of SpaceX’s plans to attempt to recover the Falcon 9’s first stage fully intact after the mission. After the first stage separates during launch, it will attempt to make a powered landing on an “autonomous spaceport drone ship,” a platform about 90 meters long and 50 meters wide in the Atlantic Ocean several hundred kilometers from the launch site.
That attempted landing is the next step in efforts by the company to recover and potentially reuse the Falcon 9’s first stage. Company officials, though, emphasized that the recovery test is secondary to the Dragon mission.
“I do expect attention on the first stage maneuvers and landing,” Hans Koenigsmann, vice president for mission assurance at SpaceX, said at the prelaunch briefing. “The main mission is absolutely to get cargo to the station.”
Koenigsmann and other company officials, including SpaceX Chief Executive Elon Musk, have stated that they expect, at best, only a 50 percent chance of successfully landing the stage on the ship on this flight. While SpaceX has brought first stages back to the ocean surface, this attempt will require a much greater landing accuracy than previous efforts.
However, in a question-and-answer session Jan. 5 on the website Reddit.com, Musk backed away from his 50-percent prediction. “I pretty much made that up,” he said. “I have no idea.”